1. Field of the Invention
The present invention relates to an injection moulding process, articles moulded by the process, and an injection moulding apparatus.
2. Description of the Related Art
Injection moulding of thermoplastics to create a product requires the creation of a separable mould. The mould normally comprises two mould parts and these mould parts may incorporate movable core inserts for the moulding of intricate shapes having undercuts.
Generally, acute undercuts in a moulding are not possible without a complicated mould construction which results in expensive tooling costs. In addition such moulds can take many months to produce. Even if a mould is produced for providing undercuts, the number of undercuts provided will be restricted such that, in the main, only straightforward geometrical snapes are produced using these techniques.
These drawbacks become more apparent when articles of non-geometric random shape are to be moulded. Such articles may for instance be models of animal shapes.
Heretofore, injection moulded models of animal shapes made from plastics have lacked realistic detail in shape due to the inability of conventional injection moulding techniques to produce many randomly shaped undercuts and fine detail. In addition since the mould cavity in the injection mould parts is defined by metal it has to be shaped using erosion techniques such as spark erosion or pantography and consequently it is not possible to accurately recreate the fine detail of an original, artistically, created sculpture.
In addition it will be appreciated that because of the high cost of creating injection moulds it is not economically practical to produce a relatively small number of mouldings of one particular model and is similarly not economically practical to produce a large number of moulds for creating a wide variety of such models.